Please can anyone help me for this circuit design that require the circuit to on the LED for 180 seconds and then off. this circuit utilises 1hz clock through 2 74LS163 counter and only counts for 180 secs.

I have posted the circuit of the 8 bit counter. i need to design the circuit to enable it to count 180 seconds using logic circuits and flip flops. it would be kind for anybody to guide me to design this circuit. this is an important school work

Looks like you need a start signal source and a way to let that signal not only start the counters, but illuminate a LED until the counter state is the hexidecimal equivalent of 180. You will need to alter the counter circuit posted, and add to it.